This invention relates to ureteral stents, and more particularly to a novel ureteral stent that resists migration when positioned in a patient, and facilitates infusion and drainage of the renal pelvic cavity.
Ureteral stents are often used to maintain fluid drainage from the renal pelvis to the bladder when the ureter is obstructed or otherwise impaired. The ureteral stent is usually provided with a drainage means, such as a lumen for directing fluid from the renal pelvis to the bladder.
For example, one known stent has a lumen extending its entire length with open proximal and distal ends. Alternatively, as shown in U.S. Pat. No. 4,531,933, openings may be provided along the stent for communication with the lumen to aid in drainage. Another known stent includes longitudinal grooves on the outer walls that function as fluid drainage channels. However, if the openings or channels of the lumen become encrusted with residues from the fluid being drained then the drainage capability of the stent is greatly impaired.
Occasionally a patient's medical treatment may require infusion of fluid from an external source into the renal pelvis to flush stone fragments and other debris that result, for example, from extra-corporeal shock-wave stone-bursting procedures. Most stents that are used for fluid drainage purposes do not adequately flush stone bursting debris because the openings in such stents are likely to become clogged by the material that is flushed from the renal pelvis during such drainage.
It is thus desirable to provide a stent which can be used for infusion purposes and which also promotes ureteral drainage of non-liquid debris as well as fluid.
Some known ureteral stents are positioned in a patient on a temporary basis until a surgical procedure is performed, while other known stents can be left indwelling on a long-term basis as a permanent means of diverting and draining fluid.
In recent years there has been an emphasis directed toward providing a stent with stabilizing means to prevent upward or downward migration from a predetermined position in a patient. Such stabilizing means can include flexible, laterally extending barbs as shown in U.S. Pat. No. 3,938,529, opposed hook-shaped elements on the proximal and distal ends of the stent for retention, as shown in U.S. Pat. No. 4,307,723, or retention coils formed on the proximal and distal ends of the stent, as shown in U.S. Pat. No. 4,531,933.
While the known stabilizing devices enable the stent to resist migration, they do not enhance the infusion and/or drainage capability of the renal pelvis.
It is thus further desirable to provide a ureteral stent which resists migration in a patient and also enhances the infusion and drainage of the renal pelvis.